Canonical Use issue - All in SEO Pack

The plugin for wordpress All in Seo Pack has added automatically the canonical element to all the blog pages.
This is ok?
Because now I have the canonical element also on duplicate pages.
For example: on the page website.com/page355.html the plugin added the <link rel="canonical" href="example.com/page355.html" />
But the page is duplicate, so why All in Seo pack treat all the pages of the website like originals

This it seems right to you? The plugin adds the canonical element on the duplicate page, and treats this page like the duplicate is the original... and if he plugin is doing this to all the pages... what is the original page after all?

So I am waiting a response from someone who actually understands what I mean... and of course understands what is canonical all about.. no just people who watch a matt cutts video on youtube and they say that are seo gurus..

I am assuming from your post that you have two pages (one a duplicate of the other) with different canonical tags.

Grizzler is correct that the canonical tag is to reduce issues associated with duplicate pages, but the duplicated page should have the canonical tag that refers to the original page, not just its own URL.

If you do have two URLs that are duplicates with their own (same URL) canonical tags then yes you do have an issue and it is an error of the plug in.

This it seems right to you? The plugin adds the canonical element on the duplicate page, and treats this page like the duplicate is the original... and if he plugin is doing this to all the pages... what is the original page after all?

I guess your right, i don't understand jibber jabber. You kind of answered the question already at the end, what is the original page? When you know add it to the plugin, it should solve the problem.